EN
MySQL - WHERE clause
0 points
In this article, we would like to show you how to use WHERE
clause in MySQL.
Quick solution:
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SELECT `column1`, `column2`, ...
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FROM `table_name`
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WHERE condition;
To show how the WHERE
clause works, we will use the following table:
Note:
At the end of this article you can find database preparation SQL queries.
In this example, we will display information about every user whose salary is greater than 3000.
Query:
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SELECT * FROM `users` WHERE `salary` > 3000;
Output:
In this example, we will display information about every user whose name is John.
Query:
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SELECT * FROM `users` WHERE `name` = 'John';
Output:
Note:
MySQL requires single quotes (
''
) around text values.
create_tables.sql
file:
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CREATE TABLE `users` (
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`id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
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`name` VARCHAR(50) NOT NULL,
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`surname` VARCHAR(50) NOT NULL,
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`department_id` INT(10) UNSIGNED,
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`salary` DECIMAL(15,2) NOT NULL,
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PRIMARY KEY (`id`)
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);
insert_data.sql
file:
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INSERT INTO `users`
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( `name`, `surname`, `department_id`, `salary`)
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VALUES
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('John', 'Stewart', 1, '3512.00'),
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('Chris', 'Brown', 2, '1344.00'),
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('Kate', 'Lewis', 3, '6574.00'),
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('Ailisa', 'Gomez', NULL, '6500.00'),
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('Gwendolyn', 'James', 2, '4200.00'),
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('Simon', 'Collins', 4, '3320.00'),
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('Taylor', 'Martin', 2, '1500.00'),
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('Andrew', 'Thompson', NULL, '2100.00');